Unless otherwise indicated herein, the materials described herein are not prior art to the claims in the present application and are not admitted to be prior art by inclusion in this section.
Some optical communication systems implement wavelength division multiplexing (WDM) in which multiple optical signals on distinct wavelength/frequency channels are transmitted over the same optical fiber. One WDM architecture is a 2-fiber WDM ring in which a first set of multiple optical signals traveling in one direction, arbitrarily referred to herein as eastbound optical signals, are transmitted over one optical fiber, and a second set of multiple optical signals traveling in an opposite direction, arbitrarily referred to herein as westbound optical signals, are transmitted over a different optical fiber. A corresponding multiplexer at an input to each optical fiber spatially combines the eastbound or westbound optical signals from different communication modules into a corresponding one of the optical fibers. A corresponding demultiplexer at an output of each optical fiber spatially separates the eastbound or westbound optical signals and distributes individual optical signals to different communication modules.
Some WDM architectures assign the various eastbound/westbound optical signals to the ITU-T C-band and/or the ITU-T L-band, each of which can accommodate 50 channels at 100 gigahertz (GHz) channel spacing. Some legacy WDM architectures have 100 GHz multiplexers and/or demultiplexers. Assuming 40 westbound optical signals and 40 eastbound optical signals in the 2-fiber WDM ring architecture described above, the use of different optical fibers for eastbound versus westbound optical signals means frequency channels can be re-used across the optical fibers as long as each frequency channel is only used once per optical fiber such that all 80 eastbound and westbound optical signals can be accommodated in the C-band. However, the 2-fiber WDM ring architecture requires two separate optical fibers.
Other WDM architectures can be implemented with a single bidirectional optical fiber. For instance, if the channel spacing is reduced to 50 GHz, all 80 eastbound/westbound optical signals can be accommodated in the C-band on a single bidirectional optical fiber. Such a configuration requires a 50 GHz multiplexer/demultiplexer at each end of the bidirectional optical fiber, which may be more costly than 100 GHz multiplexers/demultiplexers.
Alternatively, the channel spacing for 80 total eastbound/westbound optical signals in a single bidirectional optical fiber can be kept at 100 GHz if channel assignments are extended into the L-band in addition to the C-band. Such an architecture may require a more extensive and/or expensive inventory of communication modules compared to WDM architectures with channel assignments confined to the C-band.
The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one exemplary technology area where some embodiments described herein may be practiced.